It was 46 years ago today (February 13th, 1967) that the Beatles released their double A-sided single of "Strawberry Fields Forever" and "Penny Lane." The single contained two of the first three songs recorded for the group's upcoming Sgt. Pepper's Lonely Hearts Club Band album. (The other song, "When I'm 64," was saved for the album.) The songs broke the group's then unprecedented six-month stretch since their last single, "Yellow Submarine" backed by "Eleanor Rigby."

The new songs, which touched upon the group's Liverpool upbringing, were a study in contrasts, with Paul McCartney's more literal "Penny Lane" borrowing heavily from the sound of the Beach Boys' then-recent Pet Sounds album, and John Lennon's introspective "Strawberry Fields Forever" breaking new ground in both record production and song structure.

In a classic example of less being more, Beatles producer George Martin told us that the limited technology of the 1960's in no way held back the Beatles from recording timeless classics: "And I think in fact, if I had more than four tracks recording Sgt. Pepper, I don't think it would've been any better than it turned out. The music itself was so good, that no matter what you did with it -- provided you did it reasonably, technically well -- it would've survived."

Author Christopher Sanford, who wrote the recent biography titled McCartney, says that even during the Beatles days, it was McCartney who was constantly pushing the group to find new sounds in the studio: "Paul was the guy, I think, who was saying, 'You know, we can take this to a new direction. We can try these instruments that have never been tried. Let's get George Martin to have an orchestra playing out of tune!' And that was all McCartney."

The single was a global hit, with "Penny Lane" eventually topping the U.S. charts on March 18th, and "Strawberry Fields Forever" going on to peak at Number Eight.

In Britain, the single was kept from the top spot by Engelbert Humperdinck's "Release Me," marking the first time since their 1962 debut single "Love Me Do" that the Beatles failed to top the charts in their homeland.

The single, which was the Beatles' first after retiring from touring, featured the first of many Beatles songs the group never got to perform live.

In 1990, during McCartney's first performance in Liverpool since Lennon's death, he performed "Strawberry Fields Forever" in a medley with the Beatles' "Help!" and the Plastic Ono Band's "Give Peace A Chance" as a moving tribute to his fallen former partner.

McCartney introduced "Penny Lane" into his live shows on his 1993 world tour.